Apparatus for producing a pulsating current



April 17, 1962 A. FUKS APPARATUS FOR PRODUCING A PULSATING CURRENT Filed Nov. 14, 1957 INVENTOR. ixn d fat,

United States Patent Ofifice 3,030,526 Patented Apr. 17, 1962 3,030,526 APPARATUS FOR PRODUCING A PULSATING URRENT The present invention concerns an apparatus for producing a pulsating current of varying frequencies, and more particularly a pulsating current the frequency of which varies in a predetermined manner at certain intervals and for predetermined durations. Pulsating currents of this type have a particular application in the field of electro-medical treatments.

As a matter of fact it is often desirable in certain therapeutical and diagnostic processes or methods to use pulsating currents varying from time to time in frequency, and having intervals without pulses and of varying duration. In this manner it can be avoided that the person treated by these currents develops a habitual condition which could easily occur unless the above-mentioned changes in variation are provided for.

It is a main object of this invention to provide for a method and apparatus for producing the type of current described above in the most simple and efiicient manner.

With above objects in view, an apparatus according to the invention mainly comprises input means for an A.C. current of chosen basic frequency; circuit means connected with the input means and comprising several components, namely at least two branch connections for carrying each a series of half-wave pulses of like polarity, the series in one branch connection being offset in phase relative to the series in the other branch connection, and an output connection for carrying a sequence of half- Wave pulses being the combination of said series of pulses; valve means located in each of said branch connections for allowing only a half-wave of said A.C. current to pass through the particular branch connection; electron tube means located in said components of said circuit means and including valve members in circuit with said branch connections, respectively, for allowing only halfwave pulses of like polarity to pass through said branch connections, respectively, and variable resistance means in circuit with at least one of said components for temporarily suppressing the flow of said pulses in the respective component, said variable resistance means comprising a cathode and an anode spaced from each other so as to establish a resistance across the gap between them, a grid adjacent to said cathode and anode, and means for applying a variable bias potential to said grid for correspondingly varying said resistance across said gap at predetermined intervals and for predetermined durations, so that a predetermined sequence of periods of varying current conditions appears in said output connection, the pulse frequency of the current therein varying from period toperiod between Zero pulses, a pulse frequency equal to said basic frequency, and a pulse frequency equaling twice said basic frequency, depending upon in which one of said components the flow of pulses is suppressed.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 illustrates an embodiment of the invention in the form of a diagram; and

FIG. 2 illustrates diagrammatically another embodiment of the invention; and

FIG. 3 illustrates diagrammatically a component of FIGS. 1 and 2.

Referring now to FIG. 1, the apparatus in this embodiment of the invention comprises input means for an A.C. current, consisting of a transformer 1 having a primary winding connected to a line supply of A.C. current, while there are two secondary winding portions which furnish a high voltage current by way of the connections 3 and 4, respectively, to the valve electrodes of the rectifier tube 2. The center tap between the secondary winding portions is connected to an output connection 5.

The whole arrangement described so far constitutes a rectifier arrangement of generally known type.

It is, therefore, evident that in operation the branch connections 3 and 4 will be passed by a pulsating current having only half-wave pulses of like polarity and spaced from each other by a half cycle, the frequency of the pulses in these two lines 3 and 4 being equal to the basic frequency of the A.C. current introduced into the transformer 1. However the output connection 5 will carry a sequence of half-wave pulses which are the combination of the pulsating currents in the lines 3 and 4 and therefore has a pulse frequency twice the basic frequency of the AC. input current. Assuming, for instance, that the A.C. input has a frequency of 50 cycles per second then the frequency of the pulsating current in the output connection 5 would be cycles per second.

According to the invention means for interrupting the flow of said pulsating currents are provided. One preferred example of an interrupter is illustrated diagrammatically in FIG. 3. This interrupter is actually a sort of switch means having a movable member 6 which is movable with respect to a stationary terminal C and has a free end that is able to make contact alternatively with one or the other of two stationary contacts D and D The member 6 is urged by bias means Z towards the left, as seen in FIG. 3, so as to engage with one portion thereof the raised cam portions of a rotary cam carrier 7. When during the rotation of the carrier 7 any one of its cams engages a cam follower portion of the switch member 6, the connection between the terminals C and D is closed. However, when there is no engagement between the above-mentioned parts then the circuit is closed between terminal C and terminal D The rotational speed of the cam carrier 7 may be chosen arbitrarily to suit the purpose set forth in the first paragraph of this specification. The individual cams along the circumference of the carrier 7 may be provided with the same or different circumferential dimensions and like wise the spacing between consecutive cams may be chosen to suit the desired conditions. The number of cams it not limited and they may be distributed in any desired manner.

interrupter means consisting mainly of a triode 25 connected, in series with a resistor 23, between the cathode of the rectifier tube 2 and the output connection 5. Terminals 24 connected with one end of resistor 23 and with a movable tap thereof, respectively, are the output terminals of the arrangement.

If in the above-described arrangement a manually operable switch 12 is placed in the branch connection 4 then the operation can be controlled in the following manner. As long as the connection 4 is interrupted by opening the switch 12, the output of pulsating current (in the above example of 50 c.p.s. input) will vary from period to period alternatively between a frequency of 50 pulses when tube 25 is conducting and 0 pulse when it is not conducting because evidently during the interruption of the flow of pulses through the connection 5, 25, 23 no current whatsoever can be furnished at the output terminals 24 at all.

persecond when tube-2; is conducting, and O WhBD it is not conducting. 7

It: has been found that in certain cases it is desirable that the transition from one form of current to the other i.e from one frequency of pulsesto another frequency of pulsesbe performed more gradually.

'Inorder to make this possible, the electron tube 25 mentioned above is employed in such a manner that interrupter means are constituted by the variable resistance existing between theanode and cathode of the tube, the resistance being variable by means of a control grid located adjacent to the gap between said anode and cathode, provided that the bias potential impressed on such a grid is changed in accordance with the requirements corresponding to the object of the present invention.

FIGS. 1 and 2 illustrate diagrammatically two such embodiments ofthe invention.

Instead of the illustrated rectifier tube other known devices of equivalent function could be used like an arrangement oftwo diodes, or two triodes, a double diode or a double triode.

For the above mentioned purpose a condenser 26 is connected in a grid circuit between the gridlof the tube 25 and its cathode. The condenser 26 is connected in series with an auxiliary control circuit which has two branches, with one switch member 6 arranged toalternatively connect one or the other of these two branches into this circuit. The one branch is a resistor 11 which] is preferably adjustable. The other branch is a similar resistor 28 which is also adjustable and is connected in series with a source of DC. potential illustrated as a battery 100. A potentiometer 29 in parallel with the battery 100permits to adjust the potential applied to the adjustable resistor 23. Itis evident that by alternatingly movingthe switch member 6 into one or the other of its abovementioned positions the condenser 26 is alternatingly charged and discharged, the speed of this discharge and charge being predetermined by thetsettings of the adjustment means controlling the variable resistors 11, 28, and 2 9. Theswitch member 6 is of the type illustrated in FIG. 3.

Accordingly, in operation the condenser 26 will be charged and discharged in predetermined intervals according to the arrangement of camson the actuator 7 V for the switch member 6. In this case, depending upon the arrangement of cams, the tube 25 will act as a conductor or as a non-conductor in the cathode circuit of the rectifier 2. Consequently, the operation of the apparatus illustrated by FIG. 1 will be generally the same as if the interrupter according to FIG. 3 were inserted in the output connection 5. However, the transition between one mode of operation and the other isv gradual according to the chosen settings of the adjustable resistors.

FIG. 2 illustrates a modification of the previous arrangement. In this case the rectification is carried. out by two-separate triodes 2a and 2b, respectively, the oathodes whereof are connected with each other and jointly connected tovthe output resistor 23 described above. In the example of FIG. 2 the circuit described below and containing the condenser 26, the switch means 6, the source of DC. potential 100 and the variable. resistors ll, 28 and 2 2, is applied only tothe tube 2a. The grid circuit of theother tube 212 contains a switchlz' and a variable potential taken from the source 15 via an adjustable resistor 14.- The variable resistor 14 permits to adjust the strength of the pulsations obtained through the branch connection, 3 and thetubc 2b. The switch 12 could be also actuated in the manner described above with respect to the switch 6. On the other hand it is quite as well possible to equip the tube 2b with exactly the same controlmeans as those shown and described with respect to the grid control of the tube 2a.

It will benotedtha n. any ase. e, str ngths. o t e amplitudes of the pulsations delivered through either one of the branch connections 3 or 4 can be adjusted by means of the variable resistors 14, 29, and in this manner another variation of the, circuit conditions can be introduced in a very simple manner so that the amplitude of one series of half-wave pulses is different from or equal to that of the other series of half-wave pulses. 'Again the adjustment of the variable resistors 11, 14, 23, 28, and 29 may be changed periodically or in any desiredmanner by mechanicalmea'ns generally similar to the devicecomposed of members 6 andt7.

If the switch member 6 of FIGS. 1 and 2 is operated t by a cam carrier 7 as shown at. a larger scale in Fl, G. 3, then of course after every full revolution of this cam. carrier the same cycle of, operations of the switch'memher 6 would repeat. In order to preventtsuch a repetition andin order to introduce even more variationsin the. type of pulsations received at the outputof theapparatus, a number of different cam carriers may be put to work, so as toact injsuccession to each other, a mechanically driven commutator or switching apparatus serving, to alternatingly put to work one or the other, of these cam: carriers,

It will be understood that each of, the, elements described above, or two or more together, may also find, a, useful application in other types of method and apparatus for producing apulsating current, differingfrom the types described above.

While the inventionhas been illustrated and described as embodied in method and apparatus for producing a pulsating current of varying frequencies, it is not intended to be limited to the details shown,,since various modifications and structural changes may be made without, departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledgereadily adapt it for Vari-- ous applications without omitting features that, from;the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of thisinvene tion and, therefore, such adaptations shouldl andjare intended to be comprehended within the meaning and range, of equivalence of the following claims,

What is claimed as new and desired tobe secured by Letters Patent is:

1. Apparatus for producing apulsating current of varying frequencies comprising,in combination, inputmeans for an AC. current of chosen basic, frequency; circuit; means connected with saidinput means and comprising.

several components, namely at least two branch :QfluectiOns for carrying each a series of half-Wave pulses of; like polarity, the series in one, branch connection being offset, in phase relative to the series in the other, branch connection, and anoutput connection for carrying a sequence of half-wave pulses being the combination of, saidseries of pulses; electron tube means located in said, components of said circuit meansv and including valve members in circuit with said branch connections, respectively, for allowing only; half-wave pulses o f like, polarity tov pass through said. branch connections, re spectively, and variable resistancemeans in: circuit with: at leastv one of said components fcmtemporarily suppressing the iiow of said pulses in the,respectivecornponent,

saidvariableresistance means comprising a' cathode and an anode spaced from each othfir so as to establish a resistance across thegap betweentthem, av gridadjacent to said cathode and anode, and means for-applying a variable bias potential to said grid for correspondingly. varying said resistance across said gap at predetermined; intervals and for predetermined, durations, so that a predetermined sequence of periods of varying currentconditions appears in saidioutput connection, the, pulse frequency of the current therein. varying from, period to.

period between zero pulses, a pulse frequency equal to said basic frequency, and a pulse frequency equalling twice said basic frequency, depending upon in which one of said components the flow of pulses is suppressed.

2. Apparatus for producing a pulsating current of varying frequencies as set forth in claim 1, wherein said means for applying a variable bias potential to said grid include a condenser connected in a grid circuit between said cathode and said grid, and means for causing alternating charges and discharges of said condenser so that the bias potential of said grid varies corresponding to the varying potentials at the terminals of said condenser.

3. Apparatus for producing a pulsating current of varying frequencies as set forth in claim 2, wherein said means for causing alternating charges and discharges of said condenser include a control circuit in series with said condenser, said control circuit comprising two branches and a switch means movable between two positions alternatively connecting one or the other branch in series with said condenser, a predetermined resistance in one of said branches, and a predetermined resistance and a source of DC. potential in the other one of said branches, and means for actuating said switch means to move between said positions at predetermined intervals and for predetermined durations, so that depending upon the position of said switch means said condenser is charged by said source of DC. potential across said resistance in said other branch, or discharged across said resistance in said one branch.

4. Apparatus for producing a pulsating current of varying frequencies as set forth in claim 3, wherein said resistances and said source of DC. potentials are adjustable for predetermining the characteristics of the grid bias changes during said charging and discharging operations.

5. Apparatus for producing a pulsating current of varying requencies as set forth in claim 3, wherein said means for actuating said switch means is a rotatable cam member having a plurality of raised cams engaging said switch member for urging the latter from one position to the other, said cams having predetermined circumferential lengths and intervals therebetween corresponding to the desired periods of charging and discharging said condenser.

6. Apparatus for producing a pulsating current of varying frequencies as set forth in claim 1, wherein said electron tube means comprise two triodes, the cathodes of which are connected to form a combined second output connection, said triodes acting simultaneously as valve means and as variable resistances.

References Cited in the file of this patent UNITED STATES PATENTS 2,465,838 Bernard Mar. 29, 1949 

